The precision of micro analytical balance is affected by the physical factors of the environment and sample
In the process of weighing using micro analytical balance, environmental and physical factors can interfere with the results of weighing, such as temperature, sample volatilization, moisture absorption, magnetic force, electrostatic interference, etc...
1. Effect of temperature change on micro analytical balance
If a one-way drift of the displayed value is found during the weighing process, it may be due to the effect of temperature changes. If there is a temperature difference between the sample and the surrounding environment, this temperature difference will result in a flow of air along the weighing vessel. Air flowing along the outside of the container creates an upward force, which leads to a false weighing result: the sample is weighed less than it actually is under dynamic buoyancy. This effect does not cease until a temperature balance is formed. Once the sample has been removed from the oven or refrigerator, it can not be weighed until the sample is at the same temperature as the laboratory or weighing room. The sample should be placed in a peeled container with the smallest possible surface area, and the weighing container should be removed with tweezers instead of a hand in the weighing chamber.
2. The influence of moisture absorption or volatilization of the sample on the results of weighing
If the value is shown to drift continuously in one direction during weighing, a volatile or hygroscopic sample may be measured. If the sample is hygroscopic, the weight will increase, and if the sample is volatile, the weight will decrease. For hygroscopic or volatile samples, use a thin-necked container, cover or plug the container, use a clean, dry weighing container, and keep the scale tray free of dust, contaminants, and water droplets.
3. The effect of electrostatic charge on the results of weighing a sample or container
If each weighing, micro analytical balance shows different weighing results or displays value instability or weighing results of poor repeatability, it can be considered that the weighing container or sample with static electricity. The effect of electrostatic phenomena will cause the weighing container to display a different weight each time, resulting in poor repeatability. High-insulation materials such as glass, and plastic weighing containers, such as easy to bring static electricity. This charge is mainly due to the sample or container in the process of handling mixing or friction, and once charged eliminating the charge will be very slow, the probability of a sample or container becoming electrostatic in dry air with a relative humidity of less than 40% increases. This can be done by turning on the humidifier or adjusting the air-conditioning system properly, placing the weighing container in a metal container and weighing it, and attempting to ground the micro analytical balance, to remove or shield static electricity from the weighing sample.
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